In general, a lumen in a subject (e.g., a human) is a passageway that can transport one or more fluids (e.g., blood, urine, air) from one area of the subject to another area of the subject. Examples of naturally occurring lumens include veins, arteries, bronchi, esophagus, ureter, and urethra. In certain instances, it may be desirable to form a man-made lumen in a subject. For example, when treating scar tissue constriction of a portion of the portal vein (e.g., portal hypertension), a lumen can be formed in the liver to provide a passageway for fluid between the portal vein and the hepatic vein. In some cases, it can be desirable to reinforce such man-made lumens with an endoprosthesis, such as a stent or a stent-graft.